Solar Terrestrial Activity Report

Last major update issued on March 6, 2012 at 05:55 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update March 2, 2012)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update March 2, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update March 2, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update March 1, 2012)]

[POES auroral activity level since October 2009 - updated March 5, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2118 [December 2011 - January 2012] - 2119 [January-February 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on March 5. Solar wind speed at SOHO ranged between 319 and 368 km/s. A low speed stream from CH506 began to dominate the solar wind late in the day.

Solar flux measured at 20h UTC on 2.8 GHz was 131.6 (increasing 24.4 over the last solar rotation). The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 8.9). Three hour interval K indices: 22232223 (planetary), 23331222 (Boulder).

The background x-ray flux is at the class C2 level.

At midnight UTC the visible solar disk had 8 spotted active regions (in 2K resolution SDO images).

Region 11423 [N16W74] was quiet and stable.
Region 11424 [N08W59] reemerged with a single spot.
Region 11428 [S17E23] developed further and could produce M class flares. The region has small magnetic delta structures in the trailing penumbra.
Region 11429 [N17E42] increased in area with nearly all spots inside a single very large penumbra (extending 7 degrees latitudinally and 9 degrees longitudinally). Umbrae near the inversion line are large and the region may be capable of producing an X10+ flare. Flares: C3.4 at 00:36, X1.1/2B long duration event peaking at 04:09 (associated with a full halo CME), C2.3 at 10:32, C5.8 at 12:13, C5.4 at 15:04, C7.8 at 15:29, C9.8 at 16:22, C4.6 at 16:50, C6.8 at 18:37, M2.1/1B at 19:16, M1.8/1B at 19:30, C1.7 at 20:15, M1.3 at 22:34, C1.6 at 23:20, C2.4 (beginning at 23:50 and peaking) at 00:04 UTC. Early on March 6 the region has already produced 3 minor M class flares.
Region 11430 [N19E26] developed further and has weak polarity intermixing in the central spot section. Flare: C4.7 at 01:06 UTC
New region 11431 [S28W35] emerged in the southwest quadrant on March 4 and got an SWPC number the next day.

Spotted regions not reported by NOAA/SWPC:
[S1504] emerged in the northeast quadrant on March 1. Location at midnight: N10W36
[S1512] emerged in the southeast quadrant on March 5. Location at midnight: S18E48

Coronal mass ejections (CMEs)

March 3: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
March 4: The long duration M2 event in region 11429 was associated with a full halo CME which could reach Earth on March 6 or early on March 7.
March 5: Another full halo CME was observed after the X1 event. The CME could reach Earth on March 7.

Coronal holes

Coronal hole history (since October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent, elongated coronal hole (CH506) in the southern hemisphere was in an Earth facing position on March 3-4.

The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using this method, the extent and intensity of both CHs are consistent with other data sources.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair to good.

Forecast

The geomagnetic field is expected to be quiet to active with a chance of minor storm intervals on March 6-7 due to effects from CH506 and the CMEs observed on March 4 and 5. Quiet to unsettled is likely on March 8.

1) Effects from a coronal hole could reach Earth within the next 5 days. When the high speed stream has arrived the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.

Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.

Active solar regions

Click on image for higher resolution image) Compare to the previous day's image

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.

Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.

Active region	Date numbered detected	Spot count			Location at midnight	Area	Classification		SDO / HMI 4K continuum image with magnetic polarity overlay		Comment
		SWPC	STAR SDO				SWPC	STAR	Current	Previous
			2K	1K
11423	2012.02.22 2012.02.23	1	1	1	N16W75	0120	HSX	HSX
11424	2012.02.24		1		N08W59	0000		AXX
S1496	2012.02.27				N10W52						plage
S1498	2012.02.28				N32W46						plage
S1500	2012.02.29				N10W01						plage
11427	2012.02.29 2012.03.01				N15W59						plage
S1503	2012.03.01				N12W32						plage
S1504	2012.03.01		1		N10W36	0000		AXX
S1505	2012.03.02				S27E12						plage
11428	2012.03.02 2012.03.03	14	28	11	S17E21	0250	DAI	DAC			beta-gamma-delta area: 0550
11429	2012.03.02 2012.03.03	20	38	16	N17E41	0770	DKC	DKC			beta-delta area: 1800 reversed polarities
S1508	2012.03.02				S18W57						plage
S1509	2012.03.03				S10W00						plage
11430	2012.03.04	14	19	11	N20E25	0090	DAO	DAI			beta-gamma
11431	2012.03.04 2012.03.05	6	11	7	S27W36	0010	BXO	DRI			area: 0050
S1512	2012.03.05		1	1	S18E48	0000		AXX
Total spot count:		55	100	47
Sunspot number:		105	180	107	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		80	128	75	(Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number):		63	63	59	k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) for STAR SDO 2K, k = 0.55 for STAR SDO 1K

Monthly solar cycle data

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official SIDC international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the preliminary daily SWPC ap indices. Values in red are based on the official NGDC ap indices.

This report has been prepared by Jan Alvestad. It is based on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.

SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.